Simplify the following expression: $z = \dfrac{3}{10t} + \dfrac{1}{8t}$
In order to add expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $10t$ and $8t$ $\lcm(10t, 8t) = 40t$ $ z = \dfrac{4}{4} \cdot \dfrac{3}{10t} + \dfrac{5}{5} \cdot \dfrac{1}{8t} $ $z = \dfrac{12}{40t} + \dfrac{5}{40t}$ $z = \dfrac{12 +5}{40t}$ $z = \dfrac{17}{40t}$